Exoplanet found right next door in Alpha Centauri
arstechnica.com
arstechnica.com
Originally, we estimated that habitable planets were very rare. Then we discovered exoplanets, and soon after, habitable exoplanets.
Drake also started by looking for radio signs of intelligent life. Now we humans use frequency-hopping burst digital transmissions and the power level is much lower, so detecting another planet by its radio signature seems a lot less likely.
Since earth has been habitable for at least 3 billion years [2], what is the probability that intelligent life (in our galaxy) is aware of this planet and wants to look at it? My back-of-napkin estimate is that we are out on a limb of the galaxy and therefore very visible.
Maybe we'll start seeing advances in telescopic technologies and analyses in the years to come -- to pick up on more complex periodic motion of the more complex solar systems.
Not knowledgable enough in the area to know if this would be worth doing.
In order to detect Venus or Earth it would require around a 1 in 100 chance alignment of the orbital plane relative to the observer to be detectable via the transit method. Jupiter would be detectable through radial velocity techniques but it would take a minimum of 12 years to confirm a single orbit and more likely it would take at least 2 orbits for a proper confirmation. And even so it would be a coin flip on whether the orbital plane was aligned properly to be detectable at all.
With the increased sensitivity of the new instrumentation used to detect the Alpha Centauri B planet things are improved slightly but still the chances of detecting an Earth-clone via radial velocity aren't that great.
(edit): This spectrometer is supposed to be capable of detecting an earth-clone, starting around 2016:
http://en.wikipedia.org/wiki/ESPRESSO
This graph shows its predicted sensitivity (green line for a sun-like star), compared to exoplanets previously detected by the same method (gray circles), and solar system planets for reference:
http://espresso.astro.up.pt/images/content/science/image012....
For radial velocity the signal detected is proportional to the sine of the orbital inclination. The detectability of Jupiter depends highly on which instruments are being used for observation. My "coin flip" estimate was just a SWAG. If you make use of the best radial velocity detection systems today which have a sensitivity of around 1 m/s and compare that against the maximum 13 m/s radial velocity that Jupiter imparts on the Sun then you end up with much higher chances of detection (80+%) assuming a random relative orbital inclination, but that assumes there aren't any other sources of noise involved.
Thus the answer to Drake and the filter question is no one is around because there is an exit to a more interesting universe.
1) "I truly wish I could answer that question." - Having recently re-kindled an interest in space left dormant since childhood, I'm thinking this is the kind of thing I could happily dedicate my life to.
2) "I wonder if a hybrid of Google Answers and Kickstarter to answer this kind of interesting question could thrive?" - Apparently, there have been a few attempts at the latter part at least[1][2], but the list of projects is pretty short. Crowd-funded research with open-access findings seems like potentially wonderful thing.
I'm not a fan of the Drake Equation. The "equation results" section of the wikipedia page shows the range of variability: there may be anywhere from hundreds of millions of civilizations in our galaxy, to maybe we're the only one in the entire universe (a difference of close to 30 orders of magnitude), based on different guesses for some of the other parameters. Both sets of numbers are using the current understanding that we can discover exoplanets etc. and that they're not terribly rare. Prior to that understanding, estimates varied by another 5-10 orders of magnitude.
In other words, these newer discoveries don't get us particularly close to a definitive answer from the Drake Equation. We still don't know whether there's intelligent life at millions of stars in each of billions of galaxies, or if it's possibly just us.
The only sort of data that would let us actually use it to generate a meaningful answer would be the discovery of more intelligent life.
Yes but since we don't have any of those discoveries the Drake equation is really the best we can do right now.
In fact the less-than-helpful results are a useful reminder of Karl Poppers maxims
-- Homer Simpson
When you're multiplying a bunch of non-zero quantities, that's the only possibility. It's not really illustrative or useful, though -- particularly because the range of possible estimates still includes "we are alone in the universe".
You don't need the Drake Equation to tell you that it's reasonable to explore and search.
From a human point of view, I'm in the southern hemisphere and we will have clear skies. Alpha Centauri is still high above the horizon at this time of year. Tonight, I'm going to take my two kids outside and point out Alpha Centauri to them. I'll be able to tell them about it. Tell them, that now we know, part of what’s there. Tell them, that there is likely other worlds. Worlds more like ours orbiting that tiny, almost insignificant spark of light.
If FTL / Close to light speeds are impossible in this universe, we're just left with generation ships [1]. It seems that there is a very good chance that we'd be stuck on this rock called the earth forever. Really need to take better care of it.
[1] and generation ships are highly impractical (see http://www.antipope.org/charlie/blog-static/2009/11/designin... )
Alpha Centauri feels far away because our lifetimes are so ridiculously short, and we're so unfathomably economically poor, compared to the age of and resources available in the universe. These limitations don't have to apply to whatever our descendants will be a few centuries or millenia from now.
To them, a trip to Alpha Centauri might be a weekend lark.
Or maybe it was the Narn as they attacked Centaur who destroyed them...